OBJECTIVES: (1) Continuation of electron microscopic studies of the relationship of the mucous blanket to ciliary activity - and the effect of Vitamin A deprivation and dehydration on this. (2) To determine whether Janus green may be used as a dye to measure the secretion of mucous in the respiratory tract. (3) To determine whether Janus green staining of mucus secretion in vivo extends to either mucus secretory animals besides Sipunculus, and chickens. (4) To determine whether the blast cells which appear in the thymus following stimulation by infection with NDV, are T or B cells, and to see if they have a specific relationship to NDV infection itself. (5) To determine the effect of bursectomy and thymectomy on the interaction of NDV and Vitamin A deprivation. (6) To determine whether different strains of chickens yield different results on the synergistic effects of Vitamin A deficiency and NDV infection. BIBLIOGRAPHIC REFERENCE: Acute Newcastle Viral Infection of the Upper Respiratory Tract of the Chicken: F.B. Bang, M.D., B.G. Bang, BA and M. Foard, MA. II. The Effect of Diets Deficient in Vitamin A on the Pathogenesis of the Infection. Vol. 78 No. 3, March, l975, American Journal of Pathology.